Interference due to electromagnetic waves and static electricity has become of problem with the prevail of electronic equipment. In order to prevent the interference, such as electroconductive coating compositions, conductive plastics added by fillers, and nonwoven fabric containing metal fibers are suggested. For example, JP-A-61-225398 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses a sheet material comprising 10 to 85% by weight of metallic fiber, 10 to 85% by weight of fibrous binder, and 0 to 70% by weight of nonmetallic fiber, and JP-A-62-18799 discloses a material comprising a nonwoven fabric comprising at least 40% by weight of metallic fiber at the fiber weight of at least 20 g/m.sup.2. Among them, nonwoven fabric is advantageous in that they are lightweight, flexible, and that they have high productivity.
The nonwoven fabric can attain relatively easily the electrical control performances, however, the constituent fibers are apt to be randomly oriented and give bulkiness and highly porous structure. Therefore, the following problems are encountered:
(1) Electroconductive performance and electromagnetic interference shielding effect are not sufficiently high,
(2) It is necessary to add a large amount of electroconductive fiber to obtain sufficiently high electroconductive performance and electromagnetic interference shielding effect, resulting in increased cost and low workability or at the worse, in unabled formation of the nonwoven fabric; and
(3) It is inferior in shape stability and workability of the shaped product, and also the fuzzy appearance ascribed to the fiber limits the application.
Further, since electronic equipments are used indoors and in ships, automibiles, etc., properties such as fire retardation and the like, and moldability according to the application are required for electromagnetic interference shielding materials. No such material meeting the demand is obtained at the present.